A soloist falls on his rare 18th Century violin. But how can it be repaired so it sounds the same?

To drop a much-loved instrument is accident enough. But when it is a violin worth a cool million - and it's the tool of your trade as a virtuoso - it is unfortunate indeed.

This is the fate that befell David Garrett after performing in London in December. The German musician slipped down a flight of stairs and landed on his violin case, badly cracking the fiddle inside - a 1772 violin made by Giovanni Guadagnini, who called himself an "alumnus of Stradivarius".

A violin case acts like a skull, protecting what's inside. But if too badly shaken, the violin - like a brain - can be damaged.

It is a repair job that will take months of painstaking work to knit the cracks seamlessly back together, using tools and materials much like those used by master craftsman Antonio Stradivari himself.

"You have to very carefully make sure that the broken parts match up perfectly, so any slivers of wood that came loose are put into place," says David Morris, director of restorers J&A Beare, whose colleague in New York has seen the broken violin.

"There's a very famous Stradivarius cello that had its front replaced by a notable Spanish maker. That's the old way of restoration, to throw away the broken part and make your own replacement. Today we would piece it back together again from the original fragments."

Tools range from the traditional - chisels, knives and water-soluble fish-based glue similar to that Stradivari would have used - to the modern.

"If you walked into our workshop today, it would look like the set of a film about a violin-maker from several hundred years ago," says Mr Morris. "But we also use ultra-violet light and endoscopes, which allow you to see inside and take photos, rather than take the top off the instrument."

He likens this to keyhole surgery - where once surgeons opened up a patient, some procedures are now possible via tiny incisions.

Crack'd side to side

The broken violin will take at least eight months to repair. "There are two major cracks on the top on the table where the f-holes are. And two went straight through the soundpost, which is always the bad spot to hit," Garrett says.

"There are three major cracks from the top to the bottom, as well as a couple of cracks on the side, which don't really affect the sound that much, but they look very ugly."

What makes repairing a violin so fiddly is its arched body. Once the broken fragments are eased back into place, the next step is to apply pressure so the glue holds.

"You can't let the pieces slip out of alignment. The restorer will take days and days and months and months on this," says Mr Morris.

GUADAGNINI 1711-86

Student of Antonio Stradivari

Himself a great violin maker

Sale prices up to £1m, while Strads can fetch $5m+

Patches or studs may be inserted into the hollow body to strengthen it, but this risks changing the way notes vibrate and so altering its sound. So the restorer will make these as thin and as carefully placed as possible.

"The soundpost is vulnerable as there is so much pressure on it from the weight of the bridge, which holds up the taut strings. I'd say 80% of violins today have a patch under the soundpost. It's a weak point," says Mr Morris.

And whereas joins were once smoothed then revarnished, today the aim is to disturb as little of the original varnish as possible. There has never been a conclusive answer as to what gives a Stradivarius its distinctive bright sound, but one widely-held theory emphasises the role of the varnish.

So can an extensively repaired violin still be claimed as a Guadagnini or Stradivarius?

"It depends how much has had to be replaced, rather than restored," says Mr Morris. "If someone has a liver transplant, who are they? A Stradivarius violin with one rib of the six replaced is still a Strad. That said, the necks of all Stradivariuses are relatively new as these wear out - and they are not intrinsic to the sound."

As for Garrett, he now plays a replacement Stradivarius supplied by Mr Morris's firm, but eagerly awaits the return of his patched-up Guadagnini.

DAMAGED PARTS ON GARRETT'S VIOLIN

1. Body has several cracks running top to bottom and around sides

2. Some cracks near f-holes - so-called because of their shape - which release sound vibrations